Sensitized textiles with decreased formaldehyde odor

ABSTRACT

Superheated steam is utilized both to dry and remove free formaldehyde in a combined operation from textiles suitably impregnated with finishing agent and catalyst, thereby to produce a sensitized fabric with a formaldehyde odor which is imperceptible to response of the olfactory capacity of humans. The sensitized fabric of this invention can be used in the conventional post-cure process to yield durable press products.

United States Patent 11 1 Kullman et a1.

[ SENSITIZED TEXTILES WITH DECREASED FORMALDEHYDE ODOR [75] Inventors: Russel M. H. Kullman, Metairie;

Robert M. Reinhardt, New Orleans, both of La.

[73] Assignee: The United States of America as represented by the Secretary of Agriculture, Washington, DC.

[22] Filed: Dec. 21, 1971 [21] Appl. No.: 210,572

[52] US. Cl 8/186, 8/187, 117/119.8, 1l7/139.4, 117/143 A [51] Int. Cl D0,6m 13/12 [58] Field of Search l17/139.4, 143 A, 117/145,l19.8;8/115.6,116.3, 186

[56] References Cited UNITED STATES PATENTS 1/1956 Reibnitz et a1 117/143 A 8/1963 Ullman 1l7/139.4 X

[ Oct. 30, 1973 3,116,967 l/1964 Goldstein et a1 117/1 39.4 X 3,144,299 8/1964 Frick et a1.

3,420,702 l/1969 Spangler 1l7/139.4 3,445,279 5/1969 Abrahams et al 1 17/143 A 3,617,198 l1/1971 Reid et a1. 1l7/l39.4 X 3,666,400 5/1972 Lofton et a1... 117/139.4 X 2,859,136 11/1958 Marsh et a1 l17/l39.4 X 3,546,006 12/1970 Verburg et a1 117/1394 X Primary Examiner-Murray Katz Assistant Examiner-Theodore G. Davis Atl0rney-R. Hoffman et a1.

[57] ABSTRACT 12 Claims, 1 Drawing Figure PAIENTEUBN 30 m5 DRYING OF COTTON PRINTCLOTH WITH SUPERHEATED STEAM 0 EH zoo E5202 DWELL TIME,I IIN.

SENSITIZED TEXTILES WITII DECREASED FORMALDEHYDE ODOR A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

FIELD TO WHICH THIS INVENTION RELATES This invention relates to a method of producing sensitized fabric with decreased formaldehyde odor for post-cure durable press productspSpecifically, this invention relates to a method wherein sensitized fabrics are produced with low formaldehyde odor (imperceptible to human olfactory response) in a one step operation by use of superheated steam.

DEFINITIONS- By sensitized fabric we mean the use of the term as employed in the textile finishing and garment fabrication industries. A sensitized fabric is one that (1) has been impregnated with afini shing' agent, usually a -methylol amide type crosslinking agent, capable of proture in'which it is cut to pattern, sewn, trimmed, then shaped by pressing to introduce creases, pleats, etc., and to smooth the garment in its final configuration. The sensitized fabric in the form of the shaped garment is then cured, usually in an oven, to affect reaction of the finishing agent and the textile material of the garment to make the shape or configuration durable to wearing and laundering.

Post-cure processing refers to that class of finishing treatments which impart durable press properties to the textile product through a postponed cure of the sensitized cloth after the textile product has beenmade up into a garment or other apparel or household item. The term is widely used in the textile industry; however, the terms deferred cure and delayed cure also have been applied to this type of durable press process.

Free formaldehyde is the formaldehyde that is unreacted and is therefore free to volatilize from the sensitized fabric. The release of free formaldehyde can cause objectionable response, i.e., lachrymatory and sometimes allergenic, from those who come into proximity of the material. Determinations of free formaldehyde on textiles and formaldehyde release=are means used to quantify formaldehyde odor.

superheated steam is steam at a temperature above the temperature at which steam and water are in equilibrium at that pressure. At normal atmospheric pressure thiswould be steam above 212 F.

THE PROBLEM In the manufacture of post-cure durable-press garments a serious problem is the odor of formaldehyde from sensitized fabric which causes discomfort and sometimes is an actual health hazard to those who cut,

sew, and press the garments. Whenthe packages of sensitized material are opened at the garment cutting plant, free formaldehyde is slowly released to create unpleasant and potentially unsafe working conditions.

i The free formaldehyde is due to (a) residual or unreacted formaldehyde which was present in the finishing solution when it was dried on the fabric or (b) to formaldehyde which has been produced due to demethylolation of the methylolated amide compound used in tinishing. Finishers would like to reduce the formaldehyde release of sensitized fabrics and to use agents which are suitable and have other desirable qualities but which are unusable because of formaldehyde release problems.

Among agents that could be utilized advantageously in the post-cure process, if formaldehyde release could be eliminated or reduced to an unobjectionable level, are the methylol carbamates. Fabric sensitized with methylolated carbamate agents can be particularly troublesome because of the presence of relatively high iconcentrations of free formaldehyde. A primary source of free formaldehyde on the sensitized fabric is the excess formaldehyde which is generally used'in preparation of the finishing agent to maximize conversion of the carbamate to the dimethylol derivative.

THE PRIOR ART In the prior art means have been proposed for reducing free formaldehyde, of finishing agents through lowering the amount of formaldehyde in preparation of the finishing agent and through reaction of the finishing agent solution with other chemicals to bind the free .formaldehyde. These chemical methods have led to undesirable collateral effects on finished fabric such as a resin builder and crosslinking agent. Curing and criti- I cal moisture levels (above l0 percentv moisture content) of fabric subjected to steaming processes are required.

We have unexpectedly found, however, that steaming with superheated steam can be employed in a onestep operation to affect simultaneous sensitization and free formaldehyde removal.

OBJECT OF THE INVENTION It is an object'of the-instant invention to provide a new and improved method for producing sensitized fabrics with decreased formaldehyde odor that may be used in post-cure finishing without adverse effect on the processing and without inducing undesirable side effects that impair utility, esthetics, value, or durability of the resulting durable press products.

HOW THE OBJECTIVE IS ACHIEVED The objective is achieved by simultaneously sensitizing and reducing odor of fabric impregnated with a formaldehyde-containing formulation or formaldehyde-derivative-containing formulation through exposure to superheated steam. Steaming thus reduces moisture content of the web fabric while releasing and carrying away free formaldehyde. Steam sensitization thus sensitizes the fabric and reduces free formaldehyde without the necessity (l of presensitization prior to formaldehyde removal, (2) of any change in the preparation of the finishing agent, (3) of additional reaction of the finishing agent solution with other chemical agents, (4) of any fixation of a resin former to prevent fiber collapse, (5) of an additional drying step after steaming, or (6) of any other modification of the conventional post-cure durable press process. Because of the absence of such changes and modifications, steaming accomplishes the objective of sensitization and formaldehyde odor reduction without effect on the desirable characteristics of the finish and without introducing additional undesirable characteristics.

Our investigations have revealed that fabric may be dried sufficiently to effect sensitization and removal of free formaldehyde during the process of steaming with superheated steam. We have found that the steaming time must be determined for the steam temperature employed in the process to achieve drying or sensitization such that the resultant sensitized fabric has moisture contents of from about 10 percent to a lesser moisture content of about three percent. The temperature of the steam employed in the process may be varied depending on equipment availableto an operator. The efficacy of steaming is a function of steam temperature. Thus, the higher the steam temperature employed the more rapid is the lowering of the'moisture content of the fabric and removal of free formaldehyde.

Although ourpreferred embodiments are illustrated by the examples, it is also feasible to operate on either side of the preferred figure; for example, we have found that a range of about from five to percent of the weight of the crosslinking agent in the formulation, and of about 0.3 to three percent of the weight of catalyst selected from Lewis Acid type catalysts normally employed in durable press finishing operations, can be useful.

SUMMARY OF THE INVENTION The instant invention can be described as a method which provides a means of achieving a sensitized fabric with low free formaldehyde content, said fabric that is intended for post-cure processes (where cure is postponed until the desired configuration has been established in the sensitized fabric) to yield durable press textile products. The said method consists of subjecting fabric impregnated with a crosslinking agent and catalyst to superheated steam for selected periods of time such that the steam removes moisture and formaldehyde odor simultaneously and results in a sensitized fabric. The sensitized fabric produced by the method of this invention may be used in the post-cure durable press process without additional modifications to yield a durable press product without introduction of undesirable effects.

The detailed description and specific examples that follow are provided merely to illustrate the invention as well as preferred embodiments. These illustrations should not be construed as limiting the scope of the instant invention in any manner whatever. Numerous changes and modifications within the spirit of the invention will become apparent to those skilled in the art.

EXAMPLE 1 A cotton fabric was passed into and through a solution containing 10 percent (wt/wt) dimethylol methyl carbamate and 0.6 percent (wt/wt) zinc nitrate hexahydrate, the excess squeezed off, and the process was repeated to ensure thorough impregnation. A portion of the wet, impregnated fabric was sensitized by drying in an oven at 140 F for 7 minutes. Another portion of the wet impregnated fabric was sensitized by passing the fabric through a flash ager supplied with steam for a dwell time of 5.6 minutes. The steam was superheated to 240 F and circulated by mechanical convection in the flash ager. A portion of each fabric, after sensitization, was immediately analyzed for free formaldehyde content by the procedure of Reid, Reinhardt, and Bruno (American Dyestuff Reporter 54, No. 13, 54-60 [1965]). These values are listed in the table as FF." A second portion of each sensitized fabric, immediately after sensitization, was placed in a glassjar containing 50 ml of distilled water and sealed. The jaw was placed in an oven at F (49 C) for 20 hours as specified in the AATCC Test Method 112-1968 and the formaldehyde release subsequently determined. These values are listed in the table as HCHO Released." A third portion of each sensitized portion, immediately after sensitization, was washed, dried, and then analyzed for nitrogen content by the Kjeldahl method. A fourth portion of each sensitized fabric was subsequently cured by placing in an oven for 3 minutes at320 F, then washed and'dried. i

In Table I are results of fabrics that were sensitized:

TABLE I Sensiti- Time and zation Temperature HCHO N Method of Sensitization FF Released 7 Oven 7 min./I40F 0.20 0.66 0.03 Steam 5.6 min./240F 0.00 0.09 0.04

Determined after sample was washed Conventional method New method In Table II are results of fabrics that were cured after sensitization:

TABLE II WRA, Brk. Sensitization W+F Str. Str. Retention in Method N Deg. W, lb. Chlorination- Scorch test, Oven 0.56 276 36.6 99 Steam 0.61 255 40.6 99 Untreated 191 48.7 99

The remarkable reductionin free formaldehyde and formaldehyde release due to steam sensitization is illustrated in Table I. The nitrogen values show that fixed reagent is not a necessity in the steaming process. The

EXAMP E 2 A cotton fabric was impregnated with a solution identical to that in Examplel, Portions of the wet, im-

pregnated fabric were steam sensitized for different dwell times and steam temperatures. Portions of each sensitized fabric were analyzed for free formaldehyde content and formaldehyde release as in AATCC Test Method 112-1968 and the results appear in Table III.

TABLE III Time and Temperature I-ICHO of sensitization FF Released 8.3 min./240F steam 0.00 0.09 2.4 min./280F steam 0.00 0.15 3.7 min./280F steam 0.00 0.12 5.5 min./280F steam 0.00 0.11 7 min.ll40F oven 0.20 0.66

TABLE IV WRA Brk.

Time & Temperature W+F Str. Str. Retention of sensitization N deg. W, lb. in chlorination- Scorch Test, 8.3 min/240F steam 0.56 257 4| .7 94 2.4 min/280F steam 0.65 258 41.3 100 3.7 min/280F steam 0.61 267 43.3 100 5.5 min/280F steam 0.61 249 42.0 92 Untreated 191 48.7 99

These results clearly show that improvement in wrinkle recovery angles required in post curing of sensitized fabrics to develop durable press properties is achieved using the new process.

EXAMPL 3 A fabric was impregnated by padding as in Example 11511151 92199somp smsia at li 99th., A portion of the wet, impregnated fabric was sensitized by drying in an oven at 140 F for 7 minutes. Another portion of the wet, impregnated fabric was steam sensitized at 280 F for 3.8 minutes and no formaldehyde odor was noted on this sensitized fabric. The oven sensitized sample and the steam sensitized sample were creased on a steam press and then post cured in an oven at 320 F for 3 minutes. After washing and tumble drying both samples had very sharp durable creases. This further illustrates that steam sensitization is as effective as oven sensitization for preparation of sensitized fabric suitable for creasing and curing to give durable press products by the post cure process.

- EXAMPLE4 Four solutions were prepared with the following finishing agents:

Solution I dimethylol dihydroxyethyleneurea (DMDHEU) Solution II dimethylol ethyleneurea (DMEU) Solution III dimethylol 4-methoxy-5,5-dimethylpropyleneurea (modif. PU)

Solution IV bis-methoxymethyl uron (uron) Each solution contained 10% (wt/wt) of finishing agent with 0.6% (wt/wt) zinc nitrate hexahydrate catalyst. Four swatches of cotton printcloth were impregnated by padding as in Example 1. The four fabrics were then steam sensitized at 280 F for 3.6 minutes. A portion from each sensitized fabric was analyzed for free formaldehyde as in Example 1 and results are shown in Table V:

TABLE V Finishing Agent FF Used in Steam Sensitized Fabric DMDHEU I 0.01 DMEU 0.01 Modif. PU 0.05 Uron 0.04

TABLE VI Finishing Agent DP Crease WRA, W+F Used Appearance Appearance deg. DMDHEU 4.5 5 275 DM EU 2.0 2 1 82 Modif. PU 4.5 5 251 Uron 4.5 5 262 These results show that the new sensitization method is effective for preparation of durable press products by the post cure process with selected finishing agents. It is not effective with DMEU.

EXAMPLE 5 A cotton printcloth was impregnated by padding to about 96 percent wet pickup of water (49 percent moisture content) and then passed for various dwell times through steam at 240 and 280 F. Actual moisture contents of the steamed fabrics were determined and are shown in the Figure.

This demonstrates that steaming was sufficient to dry wet fabrics to moisture levels suitable for use in sensitizing fabric.

We claim:

1. A method of sensitizing a cellulosic textile for use in the preparation of a post-cure durable-press product while simultaneously rendering the textile free of formaldehyde odor, comprising impregnating the textile with a formulation containing a methylol amide crosslinking agent for cellulose and a catalyst for effecting crosslinking of the cellulose by said crosslinking agent, and subjecting the resulting wet, impregnated textile, now containing free formaldehyde, to superheated steam at a temperature of about from 240 to 280 F. for about from 2 to 8 minutes to yield a sensitive cellulosic textile having a moisture content of about from 10 to three percent moisture, a formaldehyde odor which is imperceptible to the response of the olfactory capacity of humans, and which is in a condition suitable for use in a post-cure durable-press process.

2. A method of sensitizing a cellulosic textile for use in the preparation of a post-cure durable-press product while simultaneously rendering the textile free of formaldehyde odor, comprising:

a. impregnating the cellulosic textile with a formulation containing about from five to 20 percent of a cellulose crosslinking agent selected from the group consisting of dimethylol methyl carbamate, dimethylol dihydroxyethyleneurea, dimethylol-4- methoxy-S,5-dimethylpropyleneurea, and bismethoxymethyluron, and about from 0.3 to three percent of a zinc nitrate hexahydrate catalyst for effecting crosslinking of the cellulose by said crosslinking agent, and

c. subjecting the resulting wet, impregnated textile, now containing free formaldehyde, to superheated steam at a temperature of about from 240 to 280 F. for about from 2 to 8 minutes to yield a sensitized cellulosic textile having a moisture content of about from 10 to three percent moisture, a formaldehyde odor which is imperceptible to the response of the olfactory capacity of humans, and which is in a condition suitable for use in a post-cure durable-press process.

3. The method of claim 2 wherein the crosslinking agent is dimethylol methyl carbamate.

4. The method of claim 2 wherein the crosslinking agent is dimethylol dihydroxyethyleneurea.

5. The method of claim 2 wherein the crosslinking dimethylol-4-methoxy-5,5- 

2. A method of sensitizing a cellulosic textile for use in the preparation of a post-cure durable-press product while simultaneously rendering the textile free of formaldehyde odor, comprising: a. impregnating the cellulosic textile with a formulation containing about from five to 20 percent of a cellulose crosslinking agent selected from the group consisting of dimethylol methyl carbamate, dimethylol dihydroxyethyleneurea, dimethylol-4-methoxy-5,5-dimethylpropyleneurea, and bis-methoxymethyluron, and about from 0.3 to three percent of a zinc nitrate hexahydrate catalyst for effecting crosslinking of the cellulose by said crosslinking agent, and b. subjecting the resulting wet, impregnated textile, now containing free formaldehyde, to superheated steam at a temperature of about from 240* to 280* F. for about from 2 to 8 minutes to yield a sensitized cellulosic textile having a moisture content of about from 10 to three percent moisture, a formaldehyde odor which is imperceptible to the response of the olfactory capacity of humans, and which is in a condition suitable for use in a post-cure durable-press process.
 3. The method of claim 2 wherein the crosslinking agent is dimethylol methyl carbamate.
 4. The method of claim 2 wherein the crosslinking agent is dimethylol dihydroxyethyleneurea.
 5. The method of claim 2 wherein the crosslinking agent is dimethylol-4-methoxy-5,5-dimethylpropyleneurea.
 6. The method of claim 2 wherein the crosslinking agent is bismethoxymethyluron.
 7. The product produced by the method of claim
 1. 8. The product produced by the method of claim
 2. 9. The product produced by the method of claim
 3. 10. The product produced by the method of claim
 4. 11. The product produced by the method of claim
 5. 12. The product produced by the method of claim
 6. 